Synthesis of borosiloxane oligomers containing vinyl and epoxy groups for improving adhesion of addition-curable silicone rubber with epoxy resin

In this research, a kind of borosiloxane oligomer (BSiOVi) containing vinyl and epoxy groups, was synthesized as surface treatment agent to improve the interfacial adhesion property between addition-curable liquid silicone rubber (AL-SR) and epoxy resin (EP). The chemical structure of the BSiOVi was studied by Fourier Transform Infrared Spectra (FT-IR), Gel Permeation Chromatography (GPC), Nuclear Magnetic Resonance Spectroscopy (1H-, 13C-, 29Si- and 11B-NMR) and Thermo Gravimetric Analysis (TGA). The adhesion strength between EP and AL-SR was tested using Morphological analysis and Tensile Lap Shear test. The test results showed that the BSiOVi with vinyl and epoxy groups could significantly improve the strength of adhesion between EP and AL-SR The highest adhesion strength value (3.2 MPa) was collected from silicone rubber breakage for BSiOVi/EP/AL-SR system. Furthermore, the adhesive mechanism between EP and AL-SR was analyzed. The improvement of adhesion strength was a result of chemical bonding, because the vinyl and epoxy groups of BSiOVi could react with the active hydrogen of AL-SR and amino groups of EP surface respectively. In conclusion, the BSiOVi can solve the interfacial adhesion problems effectively and the feature of BSiOVi have great application potential to solve the adhesion problem for AL-SR with other materials possessing amino groups.